Method and apparatus for multi-user frame aggregation

ABSTRACT

An aggregated physical layer (PHY) data unit for transmission of independent data for a plurality of stations via a communication channel is generated, wherein the aggregated PHY data unit includes i) a plurality of individual PHY data units corresponding to the plurality of stations and ii) information that indicates locations of at least some of the plurality of individual PHY data units within the aggregated PHY data unit. Beamforming is controlled while the aggregated PHY data unit is being transmitted. Transmission in an omnidirectional or quasi-omnidirectional manner is performed while the information that indicates locations of at least some of the plurality of individual PHY data units is transmitting. For each of the individual PHY data units, beamforming to the corresponding station is performed while at least some of the corresponding individual PHY data unit is being transmitted.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit of the following patentapplications: U.S. Provisional Application No. 61/238,026, entitled“MULTI-USER FRAME AGGREGATION,” which was filed on Aug. 28, 2009; U.S.Provisional Application No. 61/286,550, entitled “MULTI-USER FRAMEAGGREGATION,” which was filed on Dec. 15, 2009; U.S. ProvisionalApplication No. 61/361,277, entitled “Jumbo VHT Frames,” which was filedon Jul. 2, 2010; and U.S. Provisional Application No. 61/367,221,entitled “Jumbo VHT Frames,” which was filed on Jul. 23, 2010. Theentire disclosures of all of the applications referenced above arehereby incorporated by reference herein in their entireties.

The present application is also related to the following patentapplications: U.S. patent application Ser. No. 12/869,491, entitled“METHOD AND APPARATUS FOR MULTI-USER FRAME AGGREGATION,” filed on thesame day as the present application, which is hereby incorporated byreference herein in its entirety; U.S. patent application Ser. No.12/869,733, entitled “METHOD AND APPARATUS FOR FACILITATING TRANSMISSIONOF LARGE FRAMES,” filed on the same day as the present application,which is hereby incorporated by reference herein in its entirety.

FIELD OF TECHNOLOGY

The present disclosure relates generally to communication systems and,more particularly, to wireless networks.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Wireless local area network (WLAN) technology has evolved rapidly overthe past decade. Development of WLAN standards such as the Institute forElectrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g,and 802.11n Standards has improved single-user peak data throughput. Forexample, the IEEE 802.11b Standard specifies a single-user peakthroughput of 11 megabits per second (Mbps), the IEEE 802.11a and802.11g Standards specify a single-user peak throughput of 54 Mbps, andthe IEEE 802.11n Standard specifies a single-user peak throughput of 600Mbps. Work has begun on a new standard, IEEE 802.11ac, that promises toprovide even greater throughput

SUMMARY

In one embodiment, a method includes generating an aggregated physicallayer (PHY) data unit for transmission of independent data for aplurality of stations via a communication channel, wherein theaggregated PHY data unit includes i) a plurality of individual PHY dataunits corresponding to the plurality of stations and ii) informationthat indicates locations of at least some of the plurality of individualPHY data units within the aggregated PHY data unit. Additionally, themethod includes controlling beamforming while the aggregated PHY dataunit is being transmitted, comprising i) causing transmission in anomnidirectional or quasi-omnidirectional manner while the informationthat indicates locations of at least some of the plurality of individualPHY data units is transmitting, and ii) for each of the individual PHYdata units, beamforming to the corresponding station while at least someof the corresponding individual PHY data unit is being transmitted.

In another embodiment, an apparatus comprises a physical layer (PHY)processing unit to generate a PHY data unit for transmission ofindependent data for a plurality of stations via a communicationchannel, wherein the aggregated PHY data unit includes i) a plurality ofindividual PHY data units corresponding to the plurality of stations andii) information that indicates locations of at least some of theplurality of individual PHY data units within the aggregated PHY dataunit. The PHY processing unit includes a beamforming unit to: i) causetransmission in an omnidirectional or quasi-omnidirectional manner whilethe information that indicates locations of at least some of theplurality of individual PHY data units is transmitting, and ii) for eachof the individual PHY data units, beamform to the corresponding stationwhile at least some of the corresponding individual PHY data unit isbeing transmitted.

In yet another embodiment, a method includes receiving a preamble of anaggregated physical layer (PHY) data unit via a communication channel,wherein the aggregated PHY data unit includes i) a plurality ofindividual PHY data units corresponding to a plurality of stations andii) information that indicates locations of at least some of theplurality of individual PHY data units within the aggregated PHY dataunit, wherein each individual PHY data unit after a first PHY data unitincludes a corresponding midambles. The method also includes determininga duration of the aggregated PHY data unit, and determining an expectedlocation of one of the midambles. The method additionally includescontinuing to scan the communication channel for another midamble duringthe duration of the aggregated PHY data unit when the one midamble isnot detected at the expected location.

In still another embodiment, an apparatus comprises a physical layer(PHY) processing unit to determine a duration of an aggregated PHY dataunit received via a communication channel, wherein the aggregated PHYdata unit includes i) a preamble, ii) a plurality of individual PHY dataunits corresponding to a plurality of stations, and iii) informationthat indicates locations of at least some of the plurality of individualPHY data units within the aggregated PHY data unit, wherein eachindividual PHY data unit after a first PHY data unit includes acorresponding midambles. The PHY processing unit is also configured todetermine an expected location of one of the midambles, and continue toscan the communication channel for another midamble during the durationof the aggregated PHY data unit when the one midamble is not detected atthe expected location.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a block diagram of an example wireless local area network (WLAN)communication system in which an access point (AP) transmits informationto a plurality of client stations using aggregated physical layer (PHY)data units, according to an embodiment.

FIG. 2A is a diagram of two separate PHY data units transmitted by an APto two different client stations, according to an embodiment.

FIG. 2B is a diagram of a single PHY data unit that aggregates andincludes independent data for two different client stations, accordingto an embodiment.

FIG. 3 is a diagram of an example single PHY data unit that aggregatesand includes independent data for a plurality of different clientstations, according to an embodiment.

FIG. 4 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 5 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 6 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 7 is a flow diagram of an example method for processing anaggregated PHY data unit, such as one of the example aggregated PHY dataunits of FIGS. 3-6.

FIG. 8 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 9 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 10 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 11 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 12 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 13 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 14A is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 14B is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 15A is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 15B is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 15C is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 16A is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 16B is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 16C is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 17 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 18 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 19 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 20 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 21 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 22 is a diagram of an example channel sounding exchange, accordingto an embodiment.

FIGS. 23A and 23B are diagrams of other example aggregated PHY dataunits that aggregate and include independent data for a plurality ofdifferent client stations, according to other embodiments.

FIG. 24 is a diagram of an example aggregated PHY data unit thataggregates and includes independent data for the plurality of differentclient stations, according to another embodiment.

FIG. 25 is a diagram of another example aggregated PHY data units thataggregates and includes independent data for a plurality of differentclient stations, according to other embodiment.

FIGS. 26A and 26B are diagrams of other example aggregated PHY dataunits that aggregate and include independent data for a plurality ofdifferent client stations, according to other embodiments.

FIG. 27 is a diagram of another example aggregated PHY data unit thataggregates and includes independent data for a plurality of differentclient stations, according to another embodiment.

FIG. 28 is a diagram of an aggregated PHY data unit that utilizesspatial division multiplexing (SDM) and aggregated block acknowledgmentrequest (BAR) techniques, according to another embodiment.

FIG. 29 is a diagram of an example series of aggregated PHY data unitsthat include independent data for a plurality of different clientstations and that utilizes SDM, according to another embodiment.

FIG. 30 is a diagram of an example single PHY data unit that includesdata for a single station, according to an embodiment.

FIG. 31 is a diagram of another example single PHY data unit thatincludes data for single station, according to an embodiment.

FIG. 32 is a flow diagram of an example method for generating, andcontrolling the transmission of, an aggregated PHY data unit, accordingto an embodiment.

FIG. 33 is a flow diagram of another example method for generating, andcontrolling the transmission of, an aggregated PHY data unit, accordingto another embodiment.

FIG. 34 is a flow diagram of another example method for generating, andcontrolling the transmission of, an aggregated PHY data unit, accordingto another embodiment.

FIG. 35 is a block diagram of an example PHY processing unit that isutilized in some embodiments.

FIG. 36 is a flow diagram of an example method for processing a receivedaggregated PHY data unit, according to one embodiment.

FIG. 37 is a flow diagram of another example method for processing areceived aggregated PHY data unit, according to another embodiment.

FIG. 38 is a block diagram of an example A-MPDU frame format, accordingto an embodiment.

FIG. 39 is a flow diagram of an example method for controllingtransmission in a wireless network, according to an embodiment.

FIG. 40 is a flow diagram of another example method for controllingtransmission in a wireless network, according to another embodiment.

FIG. 41 is a flow diagram of another example method for controllingtransmission in a wireless network, according to another embodiment.

FIG. 42 is a flow diagram of an example method for controllingtransmission in a wireless network, according to an embodiment.

DETAILED DESCRIPTION

In embodiments described below, wireless network devices such as anaccess point (AP) and client devices of a wireless local area network(WLAN) transmit data streams between the AP and the client devices. Toenhance overall throughput, the AP aggregates independent data intendedfor a plurality of respective client devices into a single physicallayer (PHY) data unit, in some embodiments. In other embodiments, the APand/or a client device utilize enhancements to enable transmission oflarge data units, such as PHY data units or media access control (MAC)data units. As one example, an AP transmits a single PHY data unit thatincludes one or more midambles in addition to a preamble, in someembodiments. As another example, in other embodiments, a minimummodulation coding scheme by which to transmit a data unit is determinedbased on a size of the data unit. In another embodiment, devicesnegotiate a maximum PHY data unit size to be used, for example, for aparticular traffic category, for a particular traffic stream, for ablock acknowledgment (BA) session, etc.

FIG. 1 is a block diagram of an example WLAN 10 in which devices such asan AP 14 and client devices 25 exchange information using OFDM(Orthogonal Frequency-Division Multiplexing) techniques in a MIMO mode,according to an embodiment. The AP 14 includes a host processor 15coupled to a network interface 16. The network interface 16 includes amedium access control (MAC) processing unit 18 and a physical layerprocessing unit 20. The PHY processing unit 20 includes a plurality oftransceivers 21, and the transceivers are coupled to N antennas 24. InFIG. 1, the AP has the same number of transceivers 21 as antennas 24,but in other embodiments, the AP 14 includes different numbers oftransceivers 21 and antennas 24. In FIG. 1, three transceivers 21 andthree antennas 24 are illustrated, but in other embodiments, the AP 14includes different numbers of transceivers 21 and antennas 24. (e.g., 1,2, 4, 5, 6, 8, etc.) In one embodiment, the MAC processing unit 18 andthe PHY processing unit 20 are configured to operate according to acommunication protocol generally similar to the IEEE 802.11ac Standard(now in the process of being standardized), for example. Additionally,in some embodiments, the PHY processing unit 20 is configured toaggregate independent data intended for a plurality of respective clientdevices into a single PHY data unit. In other embodiments, the MACprocessing unit 18 and/or the PHY processing unit 20 are configured toutilize enhancements to enable transmission of large data units. Inother embodiment, the MAC processing unit 18 and/or the PHY processingunit 20 are configured to operate according to another communicationprotocol different than the IEEE 802.11ac Standard, but that supports orspecifies to aggregate independent data intended for a plurality ofrespective client devices into a single PHY data unit and/orenhancements to enable transmission of large data units. Hereinafter,for convenience, a communication protocol that supports or specifiesaggregating independent data intended for a plurality of respectiveclient devices into a single PHY data unit and/or enhancements to enabletransmission of large data units is referred to herein as a “very highthroughput protocol” or a “VHT protocol.”

In another embodiment, the MAC processing unit 18 and the PHY processingunit 20 are also configured to operate according to communicationprotocols such as the IEEE 802.11n Standard and/or the IEEE 802.11aStandard in addition to the VHT protocol. The IEEE 802.11a Standard isreferred to herein as a “legacy protocol,” and the IEEE 802.11n Standardis referred to herein a “high throughput protocol,” or an” “HTprotocol,” which is also a legacy protocol. In other words, the IEEE802.11a and the IEEE 802.11n Standards are examples of “legacyprotocols,” as that term is used herein.

A client device 25-1 includes a host processor 26 coupled to a networkinterface 27. The network interface 27 includes a MAC processing unit 28and a PHY processing unit 29. The PHY processing unit 29 includes aplurality of transceivers 30, and the transceivers are coupled to aplurality of antennas 34. Although the same number of transceivers 30and antennas 34 are illustrated in FIG. 1, the client device 25-1includes different numbers of transceivers 30 and antennas 34, in otherembodiments. Although three transceivers 30 and three antennas 34 areillustrated in FIG. 1, the client device 25-1 includes different numbers(e.g., 1, 2, 4, 5, etc.) of transceivers 30 and antennas 34 in otherembodiments. The transceiver(s) 30 is/are configured to transmitgenerated data units via the antenna(s) 34. Similarly, thetransceiver(s) 30 is/are configured to receive data units via theantenna(s) 34. The PHY processing unit 29 of the client device 25-1 isconfigured to process received data units conforming to the VHT protocoland to generate data units conforming to the VHT protocol fortransmission, according to various embodiments.

In an embodiment, one or both of the client devices 25-2 and 25-3 has astructure the same as or similar to the client device 25-1. In theseembodiments, the client devices 25 structured like the client device25-1 have the same or a different number of transceivers and antennas.For example, the client device 25-2 has only two transceivers and twoantennas, according to an embodiment.

According to an embodiment, the client station 25-4 is a legacy clientstation, i.e., the client station 25-4 is not enabled to receive andfully decode a data unit that is transmitted by the AP 14 or anotherclient station 25 according to the VHT protocol. Similarly, according toan embodiment, the legacy client station 25-4 is not enabled to transmitdata units according to the VHT protocol. On the other hand, the legacyclient station 25-4 is enabled to receive and fully decode and transmitdata units according to one or several legacy protocols.

FIG. 2A is a diagram of two separate PHY data units 62, 64 transmittedby an AP to two different client stations (STA1, STA2), according to anembodiment. Each of STA1 and STA2 responds with a respectiveacknowledgment 68, 70. The acknowledgement 68 transmitted by STA1 andthe beginning of the PHY data unit 64 to STA2 are separated by at leasta short interframe space (SIFS) 72. In one embodiment, the SIFS 72 has aduration of 16 μs in a 5 GHz channel.

The data unit 64 is designed for mixed mode situations, i.e., when aWLAN includes one or more client stations that conform to a legacyprotocol but not to the VHT protocol. The PHY data unit 64 includes aPHY preamble 78 and a payload 80. The PHY preamble 78 includes a portion82 having a legacy short training field (L-STF), a legacy long trainingfield (L-LTF) and a legacy signal field (L-SIG). L-STF is used by areceiver for packet detection, automatic gain control (AGC),synchronization, etc., L-LTF is used by the receiver for channelestimation and fine synchronization. The transmitter uses L-SIG tosignal basic PHY parameters to receiving devices. The portion 82 iscapable of being received and correctly decoded/interpreted by legacydevices, even if the other portions of the PHY data unit 64 (e.g., thepayload 80) cannot be received and/or correctly decoded by the legacydevices. Thus, for example, a legacy device can at least determine thelength/duration of the PHY data unit 64 using information included inL-SIG, for example. This allows a legacy station to wait until the dataunit 64 ends before attempting to transmit, for example.

The PHY preamble 78 also includes HT and/or VHT portions such as one ormore VHT signal fields (VHT-SIGs), a VHT short training field (VHT-STF),and one or more VHT long training fields (VHT-LTFs), etc. The HT and/orVHT portions of the PHY preamble 78 permits HT and/or VHT stations todetect, synchronize to, etc., HT and/or VHT transmissions.

In one embodiment, each of the L-STF and the L-LTF has a duration of 8μs, and the L-SIG has a duration of 4 μs. In one example scenario, theportion 82 has a duration of 20 μs, and payload 80 has a duration of 12μs with 1500 bytes at a rate of 1 gigabit per second (Gbps). Thus, insome scenarios, the portion 82 of the preamble 78 has a duration that issignificant when compared to the duration of the payload 80.

The data unit 62 has a format similar to the format of the data unit 64,in one embodiment.

FIG. 2B is a diagram of a single PHY data unit 88 that aggregates andincludes independent data for two different client stations (STA1,STA2). The single PHY data unit 88 is transmitted by the AP, in oneembodiment. The PHY data unit 88 includes the payload information of thetwo separate PHY data units 62, 64 of FIG. 2A, but only some of the PHYpreamble information of the two separate PHY data units 62, 64,according to an embodiment. The data unit 88 includes a portion 90corresponding to data for STA1 and a portion 92 corresponding to datafor STA2. Each of STA1 and STA2 responds to the single PHY data unit 88with a respective acknowledgment 94, 96.

The portion 90 generally corresponds to the PHY data unit 62 of FIG. 2A,and the portion 92 generally corresponds to the PHY data unit 64 of FIG.2A. The portion 92, however, omits the portion 82 (FIG. 2A), however.Thus, the portion 92 is at least 20 μs shorter than the data unit 64, inone scenario. Additionally, comparing FIGS. 2A and 2B, the PHY data unit88 is contiguous with no SIFS 72 between the portions 92, 94. Thus, thePHY data unit 88 has a duration at least 36 μs less than the cumulativeduration of the PHY data units 62, 64 and the SIFS 72. In an at leastsome scenarios, this provides a significant overhead reduction ascompared to the scenario of FIG. 2A.

FIG. 3 is a diagram of an example single PHY data unit 100 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to an embodiment.Single PHY data units that aggregate independent data for a plurality ofdifferent stations are referred to herein as aggregated PHY data units.The aggregated PHY data unit 100 includes a preamble 104 and payloads106, 108, 110 corresponding to STA1, STA2, and STA3, respectively. Thepayloads 106, 108, 110 are separated by midambles 112, 114. The preamble104, the payloads 106, 108, 110, and the midambles 112, 114 form thesingle integrated PHY data unit 100. In response to the aggregated PHYdata unit 100, STA1, STA2, and STA3 transmit acknowledgements 116. Ifthe aggregated PHY data unit 100 is part of a block acknowledgment (BA)session, the acknowledgments transmitted by STA1, STA2, and STA3 aretransmitted in response to a plurality of aggregated PHY data unitsincluding the aggregated PHY data unit 100.

The aggregated PHY data unit 100 is utilized by an AP that performsdifferent beamforming (or beamsteering) to STA1, STA2, and STA3,according to one embodiment. For example, the payload 106 is steered toSTA1, the payload 108 is steered to STA2, and the payload 110 is steeredto STA3.

The preamble 104 includes one or more legacy training fields (L-TFs) 120such as an L-STF, an L-LTF, etc., and an L-SIG 122. The preamble 104also includes a first VHT-SIG field 124 (VHT-SIGA (STA1)) correspondingto STA1, and one or more VHT training fields (VHT-TFs) 126 such as aVHT-STF, a VHT-LTF, etc. In one embodiment, the preamble 104 alsoincludes a second VHT-SIG field 128 (VHT-SIGB (STA1)) corresponding toSTA1. In another embodiment, the VHT-SIGB (STA1) 128 is omitted. In someembodiments in which the VHT-SIGB (STA1) 128 is omitted, the VHT-SIGA(STA1) 124 may be referred to merely as the VHT-SIG (STA1) 124.

The L-TFs 120, the L-SIG 122, and the VHT-SIGA (STA1) 124 aretransmitted in an omnidirectional or quasi-omnidirectional (hereinaftermerely referred to as “omnidirectional” for convenience) manner toimprove chances that all stations, including STA1, STA2, STA3, and anylegacy stations, receive at least the L-TFs 120 and the L-SIG 122, in atleast some scenarios. It also improves the chances that the VHT-SIGA(STA1) 124 is received by STA2 and STA3, in at least some scenarios. TheL-SIG 122 includes length and/or duration information that enables areceiving station (STA1, STA2, STA3, a legacy station, etc.) todetermine the length of the aggregated PHY data unit 100. The VHT-SIGA(STA1) 124 includes an indication of whether a midamble and anotherpayload follow the payload 106. The VHT-SIGA (STA1) 124 includes lengthand/or duration information that indicates the length/duration of thepayload 106, or the payload 106 and at least a portion of the preamble104 and thus enables a VHT receiving station (e.g., STA1, STA2, STA3) todetermine the length/duration of the payload 106 or the payload 106and/or at least the portion of the preamble 104. The length and/orduration information in the VHT-SIGA (STA1) 124 also indicates a startof the midamble 112, and thus enables a VHT receiving station (e.g.,STA1, STA2, STA3) to determine a start of the midamble 112. The VHT-TFs126, the VHT-SIGB (STA1) 128, and the payload 106 are steered to STA1(i.e., the transmitting device applies a steering vector or matrix).

The midamble 112 includes one or more first VHT-TFs 132 and one or moreVHT-SIG fields 134 (VHT-SIGA+B (STA2)) corresponding to STA2. In oneembodiment, the midamble 112 includes one or more second VHT-TFs 136. Inanother embodiment, the second VHT-TFs 136 are omitted. The VHT-SIGA+B(STA2) 134 includes an indication of whether a midamble and anotherpayload follow the payload 108. The VHT-SIGA+B (STA2) 134 includeslength and/or duration information that indicates the length/duration ofthe payload 108, or the payload 108 and at least a portion of themidamble 112 and thus enables a VHT receiving station (e.g., STA1, STA2,STA3) to determine the length/duration of the payload 108 or the payload108 and/or at least the portion of the midamble 112. The length and/orduration information in the VHT-SIGA+B (STA2) 134 also indicates a startof the midamble 114, and thus enables a VHT receiving station (e.g.,STA1, STA2, STA3) to determine a start of the midamble 114. The VHT-TFs132, the VHT-SIGA+B (STA2) 134, the VHT-TFs 136, and the payload 108 aresteered to STA2.

The midamble 114 includes one or more first VHT-TFs 140 and one or moreVHT-SIG fields 142 (VHT-SIGA+B (STA3)) corresponding to STA3. In oneembodiment, the midamble 114 includes one or more second VHT-TFs 144. Inanother embodiment, the second VHT-TFs 144 are omitted. The VHT-SIGA+B(STA3) 142 includes an indication of whether a midamble and anotherpayload follow the payload 110. The VHT-SIGA+B (STA3) 142 includeslength and/or duration information that indicates the length/duration ofthe payload 110, or the payload 110 and at least a portion of themidamble 142 and thus enables a VHT receiving station (e.g., STA1, STA2,STA3) to determine the length/duration of the payload 110 or the payload110 and/or at least the portion of the midamble 114. When the payload110 is the last payload of the aggregated PHY data unit 100, the lengthand/or duration information in the VHT-SIGA+B (STA3) 142 also indicatesthe end of the aggregated PHY data unit 100. The VHT-TFs 140, theVHT-SIGA+B (STA3) 142, the VHT-TFs 144, and the payload 110 are steeredto STA3.

The preamble 104 and the payload 106 are referred to as an individualPHY data unit in the aggregated PHY data unit 100. Similarly, themidamble 112 and the payload 108 are referred to as an individual PHYdata unit in the aggregated PHY data unit 100, and the midamble 114 andthe payload 110 are referred to as an individual PHY data unit in theaggregated PHY data unit 100. The preamble 104 indicates whether thepreamble 104 is part of an aggregated PHY data unit. Additionally, eachof the midambles 112, 114 indicates whether another individual PHY dataunit follows the individual PHY data unit to which the midamble belongs.Additionally, when an individual PHY data unit follows the individualPHY data unit to which a midamble belongs, the midamble indicates thestart of the next individual PHY data unit (e.g., the start of the nextmidamble).

In one example, length and/or duration information includes anindication of the length of data and an indication of an MCS used totransmit the data, so that the duration can be determined using thelength of data and the indication of the MCS.

FIG. 4 is a diagram of another example aggregated PHY data unit 150 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 150 is similar to theaggregated PHY data unit 100 of FIG. 3, but has a preamble 154 thatincludes one or more VHT-SIG fields 158 (VHT-SIGs (STA1)) correspondingto STA1 prior to the VHT-TFs (STA1) 126, but omits any VHT-SIGscorresponding to STA1 after the VHT-TFs (STA1) 126.

FIG. 5 is a diagram of another example aggregated PHY data unit 170 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 170 is similar to theaggregated PHY data unit 100 of FIG. 3, but has a preamble 174, amidamble 176, and a midamble 178.

The preamble 174 includes a VHT-SIGA 182 that includes informationcorresponding to STA1, STA2, STA3. For example, in one embodiment, theVHT-SIGA 174 includes information that indicates the length/duration ofthe aggregated PHY data unit 170. This may increase robustness, at leastin some scenarios, as compared to the aggregated PHY data unit 100 ofFIG. 3, in which the length/duration of the aggregated PHY data unit 100is merely indicated in the L-SIG 122.

The preamble 174 also includes a VHT-SIG field 184 that corresponds toSTA1 (VHT-SIGB (STA1)). VHT-SIGB (STA1) 184 includes an indication ofwhether another individual PHY data unit in the aggregated PHY data unit170 follows the payload 106. The VHT-SIGB (STA1) 184 includes lengthand/or duration information that indicates the length/duration of thePHY data unit corresponding to the preamble 174 and thus enables a VHTreceiving station (e.g., STA1, STA2, STA3) to determine thelength/duration of the PHY data unit corresponding to the preamble 174.The length and/or duration information in the VHT-SIGB (STA1) 184 alsoindicates a start of the PHY data unit in the aggregated PHY data unit170 corresponding to the midamble 176, and thus enables a VHT receivingstation (e.g., STA1, STA2, STA3) to determine a start of the midamble176. The preamble 174 also include second one or more VHT-TFs (STA1)186, in one embodiment. In another embodiment, the second VHT-TFs (STA1)186 are omitted.

The L-TFs 120, the L-SIG 122, and the VHT-SIGA (STA1) 182 aretransmitted in an omnidirectional manner. The VHT-TFs 126, the VHT-SIGB(STA1) 1 184, the second one or more VHT-TFs (STA1) 186, and the payload106 are steered to STA1.

The midamble 176 includes a VHT-SIG field 190 (VHT-SIGB (STA2))corresponding to STA2. The VHT-SIGB (STA2) 190 includes an indication ofwhether another individual PHY data unit in the aggregated PHY data unit170 follows the payload 108. The VHT-SIGB (STA2) 190 includes lengthand/or duration information that indicates the length/duration of thePHY data unit corresponding to the midamble 176 and thus enables a VHTreceiving station (e.g., STA1, STA2, STA3) to determine thelength/duration of the PHY data unit corresponding to the midamble 176.The length and/or duration information in the VHT-SIGB (STA2) 190 alsoindicates a start of the individual PHY data unit corresponding to themidamble 178, and thus enables a VHT receiving station (e.g., STA1,STA2, STA3) to determine a start of the midamble 178. The VHT-TFs 132,the VHT-SIGB (STA2) 190, the VHT-TFs 136, and the payload 108 aresteered to STA2.

The midamble 178 includes a VHT-SIG field 192 (VHT-SIGB (STA3))corresponding to STA3. The VHT-SIGB (STA3) 192 includes an indication ofwhether another individual PHY data unit follows the payload 110. TheVHT-SIGB (STA3) 192 includes length and/or duration information thatindicates the length/duration of the individual PHY data unitcorresponding to the midamble 178 and thus enables a VHT receivingstation (e.g., STA1, STA2, STA3) to determine the length/duration of theindividual PHY data unit corresponding to the midamble 178. When thepayload 110 is the last payload of the aggregated PHY data unit 170, thelength and/or duration information in the VHT-SIGB (STA3) 192 alsoindicates the end of the aggregated PHY data unit 170. The VHT-TFs 140,the VHT-SIGB (STA3) 192, the VHT-TFs 144, and the payload 110 aresteered to STA3.

FIG. 6 is a diagram of another example aggregated PHY data unit 200 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 200 is similar to theaggregated PHY data unit 170 of FIG. 5, and includes a preamble 204, amidamble 206, and a midamble 208. The preamble 204 includes a commonVHT-SIG 212 that includes information corresponding to STA1, STA2, STA3.For example, in one embodiment, the common VHT-SIG 212 includesinformation that indicates the length/duration of the aggregated PHYdata unit 200. This may increase robustness, at least in some scenarios,as compared to the aggregated PHY data unit 100 of FIG. 3, in which thelength/duration of the aggregated PHY data unit 100 is merely indicatedin the L-SIG 122.

The midamble 206 includes one or more VHT-SIG fields 216 (VHT-SIGs(STA2)) corresponding to STA2. The VHT-SIGs (STA2) 216 include anindication of whether another individual PHY data unit in the aggregatedPHY data unit 170 follows the payload 108. The VHT-SIGs (STA2) 216include length and/or duration information that indicates thelength/duration of the individual PHY data unit corresponding to themidamble 206 and thus enables a VHT receiving station (e.g., STA1, STA2,STA3) to determine the length/duration of the individual PHY data unitcorresponding to the midamble 206. The length and/or durationinformation in the VHT-SIGs (STA2) 216 also indicate a start of theindividual PHY data unit corresponding to the midamble 208, and thusenables a VHT receiving station (e.g., STA1, STA2, STA3) to determine astart of the midamble 208.

The midamble 208 includes one or more VHT-SIG fields 218 (VHT-SIGs(STA3)) corresponding to STA3. The VHT-SIGs (STA3) 218 include anindication of whether another individual PHY data unit follows thepayload 110. The VHT-SIGs (STA3) 218 includes length and/or durationinformation that indicates the length/duration of the individual PHYdata unit corresponding to the midamble 208 and thus enables a VHTreceiving station (e.g., STA1, STA2, STA3) to determine thelength/duration of the individual PHY data unit corresponding to themidamble 208. When the payload 110 is the last payload of the aggregatedPHY data unit 200, the length and/or duration information in theVHT-SIGs (STA3) 218 also indicates the end of the aggregated PHY dataunit 200.

In one embodiment, the common VHT-SIG 212 includes length/durationinformation for each individual PHY data unit in the aggregated PHY dataunit 200. Because the common VHT-SIG 212 is transmitted in anomnidirectional manner, including length/duration information for eachindividual PHY data unit in the aggregated PHY data unit 200 helps toensure that the length/duration information for each individual PHY dataunit is conveyed to all of STA1, STA2, STA3. In another embodiment, thecommon VHT-SIG 212 includes acknowledge/block acknowledge/response(ACK/BA/response) scheduling information for all of STA1, STA2, STA3, orjust STA2 and STA3. In other embodiments, the common VHT-SIG 212includes other information common for all of STA1, STA2, STA3, such asan indication of a number of individual PHY data units in the aggregatedPHY data unit, etc.

In the embodiments of FIGS. 3-6, at least some of the length/durationinformation that indicates a start of a next midamble is included in aVHT-SIG field that is steered to a particular station. Because of suchsteering, other stations may not properly receive the VHT-SIG field atleast in some scenarios.

FIG. 7 is a flow diagram of an example method 230 for processing anaggregated PHY data unit, such as one of the example aggregated PHY dataunits of FIGS. 3-6. The method 230 is utilized when a start of amidamble in the aggregated PHY data unit cannot be determined. This mayoccur when the length/duration information of an individual PHY dataunit in the aggregated PHY data unit cannot be determined because thelength/duration information is in a transmission steered to anotherstation, in some scenarios. This may additionally or alternatively occurwhen the length/duration information of an individual PHY data unit inthe aggregated PHY data unit cannot be determined because of noiseand/or interference, for example. The method 230 is implemented by a PHYprocessing unit of a receiver, such as the PHY processing unit 29 ofFIG. 1, in one embodiment.

At block 234, a length/duration of the aggregated PHY data unit isdetermined. In one embodiment, the length/duration of the aggregated PHYdata unit is determined using length, duration, and/or MCS information,in a preamble of the aggregated PHY data unit. For example, the length,duration, and/or MCS information is included in an L-SIG field of apreamble, in one embodiment. In another embodiment, the length,duration, and/or MCS information is additionally or alternativelyincluded in a VHT-SIG field of the preamble.

At block 236, when a start of a subsequent midamble in the aggregatedPHY data unit cannot be determined, the channel is scanned looking for amidamble. This channel scanning looking for a midamble continues until amidamble is found or until the end of the aggregated PHY data unitoccurs. Being unable to determine a start of a subsequent midamble mayoccur when a VHT-SIG field of a preamble or a current midamble is notreceived correctly. Thus, block 236 includes determining that a field ofa preamble or a current midamble that includes length/durationinformation for an individual PHY data unit in the aggregated PHY dataunit (e.g., a VHT-SIG field) was not received correctly, in oneembodiment.

In some embodiments, one or more signal fields in the preamble (e.g., aVHT-SIG field) that is/are transmitted in an omnidirectional mannerinclude(s) one or more of a) an indication of a multi-user groupidentifier (ID) that indicates stations for which payload data isincluded in the aggregated PHY data unit; b) an indication of a numberof individual PHY data units in the aggregated PHY data unit; and/or c)a sequence number/index for each station that indicates a relativeposition of the individual PHY data unit within the aggregated PHY dataunit, where the individual PHY data unit corresponds to the station. Asone example, in the embodiments of FIGS. 3-6, STA1 would have an indexof one, STA2 would have an index of two, and STA3 would have an index ofthree. In some embodiments in which a relative position of theindividual PHY data unit corresponding to the station is included, ifthe PHY data unit is not the first individual PHY data unit in theaggregated PHY data unit, the station stops receiving until theindividual PHY data unit occurs. Similarly, in some embodiments in whicha relative position of the individual PHY data unit corresponding to thestation is included, if the individual PHY data unit is not the lastindividual PHY data unit in the aggregated PHY data unit, the stationstops receiving after the individual PHY data unit occurs and for theremainder of the aggregated PHY data unit.

In some embodiments, a field that indicates a length duration of anindividual PHY data unit and also includes an indication of the stationfor which the individual PHY data unit includes data. The indication ofthe station is an address, in one embodiment. In some embodiments, if astation determines that the individual PHY data unit includes data forthe station, the station receives the remainder of the individual PHYdata unit. On the other hand, if a station determines that theindividual PHY data unit does not include data for the station, thestation stops receiving the remainder of the individual PHY data unitand then resumes receiving at the start of the next individual PHY dataunit, when appropriate.

FIG. 8 is a diagram of another example aggregated PHY data unit 250 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 250 includes a preamble 254, amidamble 256, and a midamble 258. As will be described below, thepreamble 254 includes information that indicates the start of themidamble 256 and the start of the midamble 258, and this information istransmitted in an omnidirectional manner. In other words, theinformation that indicates the start of the midamble 256 and the startof the midamble 258 is not steered to particular stations and thus ismore likely to be received by all of STA1, STA2, and STA3, at least insome scenarios.

The preamble 254 includes one or more VHT-SIG fields 262 correspondingto station 1 (VHT-SIGs (STA1) 262), one or more VHT-SIG fields 264corresponding to station 2 (VHT-SIGs (STA2) 264), and one or moreVHT-SIG fields 266 corresponding to station 3 (VHT-SIGs (STA3) 266). TheVHT-SIGs (STA1) 262 include information that indicates a length durationof the individual PHY data unit corresponding to the preamble 254, andthe VHT-SIGs (STA2) 262 include information that indicates a lengthduration of the individual PHY data unit corresponding to the midamble256. Similarly, the VHT-SIGs (STA3) 266 include information thatindicates a length duration of the individual PHY data unitcorresponding to the midamble 258. The preamble 254 also include one ormore VHT-TFs 268 corresponding to STA1 (VHT-TFs (STA1) 268).

The VHT-SIGs (STA1) 262, VHT-SIGs (STA2) 264, and VHT-SIGs (STA3) 266are transmitted in an omnidirectional manner, thus improving odds thatall of STA1, STA2, and STA3, will be able to determine length/durationinformation for all of the PHY data units in the aggregated PHY dataunit as compared to the embodiments of FIGS. 3-6, at least in somescenarios. In one embodiment, the VHT-SIGs (STA1) 262, VHT-SIGs (STA2)264, and VHT-SIGs (STA3) 266 are integrated and/or compressed ascompared to similar VHT-SIG fields in the embodiments of FIGS. 3-6.

The midamble 256 omits VHT-SIG corresponding to STA2, and the midamble258 omits VHT-SIG corresponding to STA3. In one embodiment, each of themidamble 256 and the midamble 258 only includes one or more trainingfields such as a VHT-STF and/or one or more VHT-LTFs.

FIG. 9 is a diagram of another example aggregated PHY data unit 300 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 300 is generally similar to theaggregated PHY data unit 150 of FIG. 4. The aggregated PHY data unit 300includes a preamble 304, a midamble 306, and a midamble 308. As will bedescribed below, the VHT-SIG fields that include information thatindicates the duration of the individual PHY data units within theaggregated PHY data unit 300 are each transmitted in an omnidirectionalmanner. In other words, the information that indicates the start of themidamble 306 and the start of the midamble 308 is not steered toparticular stations and thus is more likely to be received by all ofSTA1, STA2, and STA3, at least in some scenarios.

The preamble 304 includes the VHT-SIGs (STA1) 158, which are transmittedin an omnidirectional manner. The preamble 304 also includes one or morecommon VHT-TFs 312 that are also transmitted in an omnidirectionalmanner, thus providing training fields for all of stations STA1, STA2,and STA3. On the other hand, the VHT-TFs (STA1) 126 and the payload 106are steered to station 1.

A portion of the midamble 306 is transmitted in an omnidirectionalmanner. For example, the midamble 306 includes one or more commonVHT-TFs 314 and the VHT-SIGs (STA2) 134, which are transmitted in anomnidirectional manner. On the other hand, the VHT-TFs (STA2) 136 andthe payload 108 are steered to station 2.

Similarly, a portion of the midamble 308 is transmitted in anomnidirectional manner. For example, the midamble 308 includes one ormore common VHT-TFs 316 and the VHT-SIGs (STA3) 142, which aretransmitted in an omnidirectional manner. On the other hand, the VHT-TFs(STA3) 144 and the payload 110 are steered to station 3.

In one embodiment, some or all of the common VHT-TFs 314 in the midamble306 and some or all of the common VHT-TFs 316 in the midamble 308 areomitted when corresponding common VHT-TFs are included in the preamble304 (i.e., in the common VHT-TFs 312). In one embodiment, some or all ofthe VHT-TFs (STA2) 136 in the midamble 306 and some or all of theVHT-TFs (STA3) 144 in the midamble 308 are omitted when correspondingcommon VHT-TFs are included in the preamble 304 (i.e., in the commonVHT-TFs 312). In one embodiment, some or all of the VHT-TFs (STA1) 126in the preamble 304 are omitted when corresponding common VHT-TFs areincluded in the common VHT-TFs 312. In one embodiment, indications ofpositions of the VHT-SIG fields in the midambles are included in theVHT-SIGs (STA1) 158.

In some embodiments, beamsteering is not permitted when transmitting anaggregated PHY data unit. FIG. 10 is a diagram of another exampleaggregated PHY data unit 330 that aggregates and includes independentdata for a plurality of different client stations (e.g., STA1, STA2,STA3), according to another embodiment. The aggregated PHY data unit 330is generally similar to the aggregated PHY data unit 150 of FIG. 4. Withthe aggregated PHY data unit 330, however, the entire aggregated PHYdata unit 330 is transmitted in an omnidirectional manner.

FIG. 11 is a diagram of another example aggregated PHY data unit 340that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 340 is generally similar to theaggregated PHY data unit 150 of FIG. 4. With the aggregated PHY dataunit 330, however, the entire aggregated PHY data unit 340 istransmitted in an omnidirectional manner. The aggregated PHY data unit340 is generally similar to the aggregated PHY data unit 330 of FIG. 9,but omits the VHT-TFs from the midambles.

FIG. 12 is a diagram of another example aggregated PHY data unit 360that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 360 is generally similar to theaggregated PHY data unit 10 of FIG. 4. The aggregated PHY data unit 360includes a preamble 364, a midamble 366, and a midamble 368. The VHT-SIGfields that include information that indicates the duration of the PHYdata units within the aggregated PHY data unit 360 are each transmittedin an omnidirectional manner. In other words, the information thatindicates the start of the midamble 364 and the start of the midamble368 is not steered to particular stations and thus is more likely to bereceived by all of STA1, STA2, and STA3, at least in some scenarios.

The preamble 364 includes the VHT-SIGs (STA1) 158, which are transmittedin an omnidirectional manner. On the other hand, the VHT-TFs (STA1) 126and the payload 106 are steered to station 1.

A portion of the midamble 366 is transmitted in an omnidirectionalmanner. For example, the midamble 366 includes the VHT-TFs (STA2) 314and the VHT-SIGs (STA2) 134, which are transmitted in an omnidirectionalmanner. On the other hand, the VHT-TFs (STA2) 136 and the payload 108are steered to station 2. In one embodiment, the VHT-TFs (STA2) 314include a VHT-STF and only a first VHT-LTF (VHT-LTF1). On the otherhand, the VHT-TFs (STA2) 136, which are steered to STA2, include theVHT-LTFn, wherein n>1.

Similarly, a portion of the midamble 368 is transmitted in anomnidirectional manner. For example, the midamble 368 includes one ormore VHT-TFs (STA3) 316 and the VHT-SIGs (STA3) 142, which aretransmitted in an omnidirectional manner. On the other hand, the VHT-TFs(STA3) 144 and the payload 110 are steered to station 3. In oneembodiment, the VHT-TFs (STA3) 316 include a VHT-STF and only a firstVHT-LTF (VHT-LTF1). On the other hand, the VHT-TFs (STA3) 144, which aresteered to STA3, include the VHT-LTFn, wherein n>1.

FIG. 13 is a diagram of another example aggregated PHY data unit 380that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 380 is generally similar to theaggregated PHY data unit 150 of FIG. 4. In the aggregated PHY data unit380, however, each of the VHT-SIG fields 384, 386, 388 includes anindication of the station to which the respective individual PHY dataunit corresponds. In one embodiment, each of the VHT-SIG fields 384,386, 388 includes an address of the station to which the respectiveindividual PHY data unit corresponds. In these embodiments, a station,after analyzing the address information in the VHT-SIG field may stopreceiving the corresponding individual PHY data unit if the address doesnot correspond to the station, and may then wait for the next midamble.

FIG. 14A is a diagram of another example aggregated PHY data unit 400that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 400 omits midambles.

A preamble of the aggregated PHY data unit 400 includes one or moreL-TFs, and the L-SIG 122. The preamble also includes VHT-SIGs (STA1) 404and VHT-SIGs (STA2) 408. The preamble also includes VHT-TFs (STA1) 408and VHT-TFs (STA2) 410.

The aggregated PHY data unit 400 further includes a payload 414corresponding to STA1 and a payload 416 corresponding to STA2. Inresponse to the aggregated PHY data unit 400, STA1 and STA2 transmitacknowledgements 420 and 422, respectively. If the aggregated PHY dataunit 400 is part of a BA session, the acknowledgments transmitted bySTA1 and STA2 are transmitted in response to a plurality of aggregatedPHY data units including the aggregated PHY data unit 400.

The L-TFs 120, the L-SIG 122, the VHT-SIGs (STA1) 404 and the VHT-SIGs(STA2) 408 are transmitted in an omnidirectional manner. The VHT-SIGs(STA1) 404 include an indication of whether other VHT-SIGs follow theVHT-SIGs (STA1) 404. The VHT-SIGA (STA1) 404 includes length and/orduration information that indicates the length/duration of the payload414, and thus enables a VHT receiving station (e.g., STA1, STA2) todetermine the length/duration of the payload 414. The length and/orduration information in the VHT-SIGA (STA1) 404 also indicates a startof the payload 416.

The VHT-SIGs (STA2) 406 include an indication of whether other VHT-SIGsfollow the VHT-SIGs (STA2) 406. The VHT-SIGA (STA2) 406 includes lengthand/or duration information that indicates the length/duration of thepayload 416, and thus enables a VHT receiving station (e.g., STA1, STA2)to determine the length/duration of the payload 416. The length and/orduration information in the VHT-SIGA (STA2) 406 also indicates an end ofthe aggregated PHY data unit 400.

The VHT-TFs (STA1) 408 are steered to STA1, whereas the VHT-TFs (STA2)410 are steered to STA2. Similarly, the payload 414 is steered to STA1,whereas the payload 416 is steered to STA2.

FIG. 14B is a diagram of another example aggregated PHY data unit 430that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 430 is generally similar to theexample aggregated PHY data unit 400 of FIG. 14A, but the order of theVHT-TFs (STA1) 408 and the VHT-TFs (STA2) 410 are reversed. This permitsone less beamsteering transition as compared to FIG. 14A.

In the embodiments of FIGS. 14A and 14B, the VHT-SIGs 404, 406 areadjacent.

FIG. 15A is a diagram of another example aggregated PHY data unit 440that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 440 is generally similar to theaggregated PHY data unit 400 of FIG. 14A, and omits midambles. Unlikethe aggregated PHY data unit 400 of FIG. 14A, however, the VHT-SIGscorresponding to STA1 and STA2 are separated by a plurality of VHT-TFs.

In one embodiment, the preamble of the PHY data unit 440 includes asecond set of VHT-TFs (STA2) 444 after the VHT-SIGs (STA2) 406. Inanother embodiment, the second set of VHT-TFs (STA2) 444 is omitted.

FIG. 15B is a diagram of another example aggregated PHY data unit 460that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 460 is generally similar to theaggregated PHY data unit 440 of FIG. 15A, and omits midambles. Ascompared to the aggregated PHY data unit 440 of FIG. 15A, the order ofthe VHT-SIGs 404 and 406 are reversed. Similarly, the order of theVHT-TFs 408 and 410 are reversed. Further, the second set of VHT-TFs(STA2) 444 is omitted.

In one embodiment, the preamble of the PHY data unit 460 includes asecond set of VHT-TFs (STA1) 464 after the VHT-SIGs (STA1) 404. Inanother embodiment, the second set of VHT-TFs (STA1) 464 is omitted.

FIG. 15C is a diagram of another example aggregated PHY data unit 480that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 480 is generally similar to theaggregated PHY data unit 460 of FIG. 15B, and omits midambles.

As compared to the aggregated PHY data unit 460 of FIG. 15B, a set ofVHT-TFs precedes each of the VHT-SIGs 404 and 406. Additionally, acommon VHT-SIGs field 484 precedes the VHT-TFs and the VHT-SIGs 404 and406, and the common VHT-SIGs field 484 is transmitted in anomnidirectional manner. In one embodiment, the common VHT-SIGs field 484includes information indicating one or more of the length/duration ofthe aggregated PHY data unit 480, the number of payloads 414, 416, indexand/or sequence information for the payloads 414, 416, length/durationfor each of at least some of the payloads 414,416 (e.g., for allpayloads, for all payloads except the last payload, etc.).

In one embodiment, the preamble of the PHY data unit 480 includes thesecond set of VHT-TFs (STA1) 464 after the VHT-SIGs (STA1) 404. Inanother embodiment, the second set of VHT-TFs (STA1) 464 is omitted. Inone embodiment, the preamble of the PHY data unit 480 includes thesecond set of VHT-TFs (STA2) 444 after the VHT-SIGs (STA2) 406. Inanother embodiment, the second set of VHT-TFs (STA2) 444 is omitted. Inone embodiment, the preamble of the PHY data unit 480 includes thesecond set of VHT-TFs (STA1) 464 after the VHT-SIGs (STA1) 404, andincludes the second set of VHT-TFs (STA2) 444 after the VHT-SIGs (STA2)406. In one embodiment, the preamble of the PHY data unit 480 omits boththe second set of VHT-TFs (STA1) 464 and includes the second set ofVHT-TFs (STA2) 444.

FIG. 16A is a diagram of another example aggregated PHY data unit 500that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 500 is generally similar to theexample aggregated PHY data unit 400 of FIG. 14A, but the VHT-SIGs 404,406 are not adjacent, VHT-TFs corresponding to a VHT-SIGs field andprior to the VHT-SIGs field are omitted, whereas a corresponding VHT-TFsfield occurs after each VHT-SIGs field.

FIG. 16B is a diagram of another example aggregated PHY data unit 540that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 540 is generally similar to theexample aggregated PHY data unit 500 of FIG. 16A, but the order of theVHT-SIGs (STA1) 404 and the VHT-TFs (STA1) 408 is reversed, and theaggregated PHY data unit 540 includes a midamble prior to the payload416, where the preamble includes the VHT-TFs (STA2) 410.

FIG. 16C is a diagram of another example aggregated PHY data unit 570that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2), according to anotherembodiment. The aggregated PHY data unit 570 is generally similar to theexample aggregated PHY data unit 540 of FIG. 16B, but the midamble alsoincludes the VHT-SIGs (STA1) 406 prior to the VHT-TFs (STA2) 410.

Acknowledgments (ACKs) and block acknowledgments (BAs) can be utilizedwith any of the example aggregated PHY data units discussed above. FIG.17 is diagram of another example aggregated PHY data unit 600 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 600 includes a preamble 604, apayload 606 corresponding to STA1, a midamble 608, a payload 610corresponding to STA2, a midamble 612, and a payload 614 correspondingto STA3.

In response to the aggregated PHY data unit 600, the stationcorresponding to the first payload in the aggregated PHY data unit 600(i.e., STA1) transmits an ACK or BA 620. In other words, at most onestation is allowed to send an immediate acknowledgement. On the otherhand, the stations corresponding to the remaining payloads in theaggregated PHY data unit 600 (i.e., STA2, STA3) wait for anacknowledgement request, such as a block acknowledgement request (BAR).In other words, at most one station (e.g., the station corresponding tothe first payload) is allowed to send an immediate acknowledgement.

The AP transmits an acknowledgement request 624, such as a BAR,corresponding to STA2. In response to the acknowledgement request 624,STA2 transmits an ACK or BA 626. Similarly, the AP transmits anacknowledgement request 634, such as a BAR, corresponding to STA3. Inresponse to the acknowledgement request 634, STA3 transmits an ACK or BA636.

In the embodiment of FIG. 17, the ACKs and ACK requests are separatedfrom each other in time, such as by at least the SIFS.

FIG. 18 is diagram of another example aggregated PHY data unit 640 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 640 is generally similar to theexample aggregated PHY data unit 600 of FIG. 17, but the acknowledgementrequest 624 and the acknowledgement request 634 are aggregated into asingle PHY data unit 644, i.e., there is no spacing between theacknowledgement request 624 and the acknowledgement request 634, and/orno ACK/BA is transmitted by a station in between the acknowledgementrequest 624 and the acknowledgement request 634. Similar to the exampleaggregated PHY data unit 600 of FIG. 17, at most one station (e.g., thestation corresponding to the first payload) is allowed to send animmediate acknowledgement.

FIG. 19 is diagram of another example aggregated PHY data unit 680 thataggregates and includes independent data for a plurality of differentclient stations (e.g., STA1, STA2, STA3), according to anotherembodiment. The aggregated PHY data unit 680 is generally similar to theexample aggregated PHY data unit 150 of FIG. 4.

Similar to the example aggregated PHY data unit 600 of FIG. 17, at mostone station (e.g., the station corresponding to the first payload) isallowed to send an immediate acknowledgement. Other stations sendacknowledgments at times corresponding to ACK scheduling informationprovided in the aggregated PHY data unit 680. In some embodiments, theACK scheduling information is included in PHY portions of the data unit680, such as in VHT-SIGs. The ACK scheduling information includes one ormore of a starting time, a slot allocation (e.g., a starting time andduration), a sequence or index, etc., in various embodiments.

In some embodiments, the ACK scheduling information is included in MACportions of the data unit 680, such as in a MAC header duration field orsome other suitable MAC header field.

Although FIGS. 17-19 discussed ACK/BA techniques in the context ofparticular aggregated PHY data unit formats, other formats can beutilized as well, such as aggregated PHY data unit formats that omitmidambles.

FIG. 20 is a diagram of another example aggregated PHY data unit 700that aggregates and includes independent data for a plurality ofdifferent client stations (e.g., STA1, STA2, STA3), according to anotherembodiment. In one embodiment, the aggregated PHY data unit 700 istransmitted by an AP. Prior to transmitting the aggregated PHY data unit700, the AP transmits a clear-to-send-to-self (CTS-to-self) 704. TheCTS-to-self 704 includes length/duration information that indicates toother stations the length/duration of the aggregated PHY data unit 700as well as an ACK/BA period 708 following the aggregated PHY data unit700. In other embodiments, the AP additionally transmits arequest-to-send (RTS) to each station for which the aggregated PHY dataunit 700 includes a corresponding payload, and receives, in response, aCTS from each station.

In other embodiments, the AP additionally transmits a request-to-send(RTS) to each station for which the aggregated PHY data unit 700includes a corresponding payload, and receives, in response, a CTS fromeach station.

FIG. 21 is a diagram of an example series of aggregated PHY data unitsthat include independent data for a plurality of different clientstations (e.g., STA1, STA2), according to another embodiment. Prior totransmitting aggregated PHY data units 754, 758, the AP transmits aCTS-to-self 762. The CTS-to-self 762 includes length/durationinformation that indicates to other stations the length/duration of theaggregated PHY data units 754, 758 as well as associated ACK/BA periods766, 770, each following the corresponding aggregated PHY data units754, 758.

After transmitting the CTS-to-self 762, the AP transmits an aggregatedRTS 774 that includes an RTS 776 to STA1 and an RTS 778 to STA2. The RTS774 is integrated, i.e., there is no spacing between the RTS 776 and theRTS 778, and/or no CTS is transmitted by a station in between the RTS776 and the RTS 778. In response to the aggregated RTS 774, STA1transmits a CTS 784 and STA2 transmit a CTS 786. Each of the aggregatedRTS 774, the CTS 784, and the CTS 786 includes length/durationinformation that indicates to other stations the length/duration of theaggregated PHY data units 754, 758 as well as associated ACK/BA periods766, 770.

In one embodiment, STA1 transmits the CTS 784 immediately in response tothe aggregated RTS 774. In one embodiment, the aggregated RTS 774includes scheduling information for the CTS 786 so that STA2 determineswhen to transmit the CTS 786. In one embodiment, the CTS-to-self 762 isomitted.

In some embodiments, aggregated PHY data units that include independentdata for a plurality of different client stations are utilized inchannel sounding procedures. FIG. 22 is a diagram of an example channelsounding exchange 800, according to an embodiment. An AP transmitssounding information 804 to STA1 and STA2. STA1 and STA2 response withsounding feedback 806, 808, respectively.

The sounding information 804 includes a null data packet (NDP)announcement 812 to STA1 and STA2, in one embodiment. The NDPannouncement 812 to STA1 and STA2 includes an aggregated PHY data unit816, in one embodiment. The aggregated PHY data unit 816 has a formatgenerally the same as the aggregated PHY data unit 150 of FIG. 4, in oneembodiment. In other embodiments, the aggregated PHY data unit 816 hasanother suitable format. A payload 820 for STA1 includes an NDPannouncement for STA1, and a payload 822 for STA2 includes an NDPannouncement for STA2. In one embodiment, the aggregated PHY data unit816 is considered a staggered PHY data unit. With staggered sounding,spatial spreading is performed separately for training symbolsassociated with the data dimensions and the training symbols associatedwith the extra spatial dimensions (extension spatial streams in IEEE802.11n). In this way, the sounding for the extension spatial streamsmay be separated in time from the sounding for the data dimensions.Staggered sounding may be used when the number of dimensions to besounded is greater than the number of data dimensions, or space timestreams.

Aggregated PHY data unit techniques, such as the techniques describedabove, may be used in conjunction with frequency division multiplexing(FDM) techniques such as described in U.S. patent application Ser. No.12/730,651, entitled “OFDMA with Block Tone Assignment for WLAN,” filedon Mar. 24, 2010, which is hereby incorporated by reference herein inits entirety. FIGS. 23A and 23B are examples of aggregated PHY dataunits 840, 870 that employ FDM, according to some embodiments. As merelyone example, each aggregated PHY data unit 840, 870 has a bandwidth of40 MHz that is multiplexed into two 20 MHz portions for a subset of theaggregated PHY data unit 840, 870. In this example, each subset of eachaggregated PHY data unit 840, 870 generally is similar to the format ofthe aggregated PHY data unit 150 of FIG. 4, according to someembodiments. In other embodiments, each aggregated PHY data unit 840,870 has another suitable bandwidth such as 80 MHz, 120 MHz, 160 MHz,etc.

FIGS. 24 and 25 are additional examples of aggregated PHY data units900, 930 that employ FDM, according to some embodiments. As merely oneexample, each aggregated PHY data unit 900, 930 has a bandwidth of 40MHz that is multiplexed into two 20 MHz portions for a subset of theaggregated PHY data unit 900, 930. In this example, each subset of eachaggregated PHY data unit 900 is generally similar to the format of theaggregated PHY data unit 200 of FIG. 6, according to some embodiments.Also in this example, each subset of each aggregated PHY data unit 930is generally similar to the format of the aggregated PHY data unit 250of FIG. 8, according to some embodiments. In other embodiments, eachaggregated PHY data unit 900, 930 has another suitable bandwidth such as80 MHz, 120 MHz, 160 MHz, etc.

Aggregated PHY data unit techniques, such as the techniques describedabove, may be used in conjunction with spatial division multiplexing(SDM) techniques. FIGS. 26A and 26B are examples of aggregated PHY dataunits 960, 980 that employ SDM, according to some embodiments. In theseexamples, each aggregated PHY data unit 960, 980 generally is similar tothe format of the aggregated PHY data unit 200 of FIG. 6, according tosome embodiments. FIG. 27 is another example of an aggregated PHY dataunit 990 that employs SDM, according to an embodiment. In this example,the aggregated PHY data unit 990 generally is similar to the format ofthe aggregated PHY data unit 150 of FIG. 4, according to an embodiment.FIG. 27 is another example of an aggregated PHY data unit 990 thatemploys SDM, according to an embodiment. In this example, the aggregatedPHY data unit 990 generally is similar to the format of the aggregatedPHY data unit 150 of FIG. 4, according to an embodiment.

Acknowledgment techniques discussed above can also be utilized in thecontext of FDM and/or SDM techniques. FIG. 28 is a diagram of anaggregated PHY data unit 101 that utilizes SDM and aggregated BARtechniques, according to another embodiment. In this example, theaggregated BAR and response to the aggregated BAR by STA1 and STA2 aregenerally similar to the example aggregated BAR of FIG. 18, according toan embodiment. FIG. 29 is a diagram of an example series of aggregatedPHY data units that include independent data for a plurality ofdifferent client stations (e.g., STA1, STA2) and that utilizes SDM,according to another embodiment. The aggregated RTS and responsive CTSsare generally similar to the example aggregated RTS of FIG. 21,according to an embodiment.

Preamble and/or midamble techniques such as described above can also beutilized in the context of transmissions to a single station. FIG. 30 isa diagram of an example single PHY data unit 1100 that includes data forSTA1, according to an embodiment. The PHY data unit 1100 includes apreamble 1104 and data portions 1106, 1108, 1110 corresponding. The dataportions 1106, 1108, 1110 are separated by midambles 1112, 1114. Thepreamble 1104, the data portions 1106, 1108, 1110, and the midambles1112, 1114 form the single integrated PHY data unit 1100. In response tothe PHY data unit 1100, STA1 transmit acknowledgement 1116. If the PHYdata unit 1100 is part of a block acknowledgment (BA) session, theacknowledgment transmitted by STA1 is transmitted in response to aplurality of PHY data units including the PHY data unit 1100.

The preamble 1104 includes one or more L-TFs 120 such as an L-STF, anL-LTF, etc., and the L-SIG 122. The preamble 1104 also includes a firstVHT-SIG field 1120 (VHT-SIGs (STA1)), and one or more VHT trainingfields (VHT-TFs (STA1)) 1124 such as a VHT-STF, a VHT-LTF, etc.

The L-TFs 120, the L-SIG 122, and the VHT-SIGs (STA1) 1120 aretransmitted in an omnidirectional manner to improve chances that allstations, including STA1 and any legacy stations, receive at least theL-TFs 120 and the L-SIG 122, in at least some scenarios. The L-SIG 122includes length and/or duration information that enables a receivingstation (e.g., STA1, a legacy station, etc.) to determine the length ofthe PHY data unit 1100. The VHT-SIG (STA1) 1120 includes an indicationof whether a midamble and another data portion follow the data portion1106. The VHT-SIGs (STA1) 1120 includes length and/or durationinformation that indicates the length/duration of the portion 1106, orthe portion 1106 and at least a portion of the preamble 1104 and thusenables STA1 to determine the length/duration of the portion 106 or theportion 106 and/or at least the portion of the preamble 1104. The lengthand/or duration information in the VHT-SIGs (STA1) 1120 also indicates astart of the midamble 1112, and thus enables STA1 to determine a startof the midamble 1112. The VHT-TFs 1124 and the data portion 1106, andthe remainder of the data unit 1100 are steered to STA1 (i.e., thetransmitting device applies a steering vector or matrix).

The midamble 1112 includes one or more first VHT-TFs 1128 and one ormore VHT-SIGs (STA1) 1130. In one embodiment, the midamble 112 includesone or more second VHT-TFs 1132. In another embodiment, the secondVHT-TFs 1132 are omitted. The VHT-SIGs (STA1) 1130 includes anindication of whether a midamble and another data portion follow thedata portion 1108. The VHT-SIGs (STA1) 1130 includes length and/orduration information that indicates the length/duration of the dataportion 1108, or the data portion 1108 and at least a portion of themidamble 1112 and thus enables STA1 to determine the length/duration ofthe data portion 108 or the data portion 108 and/or at least the portionof the midamble 1112. The length and/or duration information in theVHT-SIGs (STA1) 1130 also indicates a start of the midamble 1114, andthus enables STA1 to determine a start of the midamble 1114.

The midamble 1114 includes one or more first VHT-TFs 1138 and one ormore VHT-SIGs (STA1) 1140. In one embodiment, the midamble 1114 includesone or more second VHT-TFs 1142. In another embodiment, the secondVHT-TFs 1142 are omitted. The VHT-SIGs (STA1) 1140 includes anindication of whether a midamble and another data portion follow thedata portion 1110. The VHT-SIGs (STA1) 1140 includes length and/orduration information that indicates the length/duration of the dataportion 1110, or the payload 1110 and at least a portion of the midamble1114 and thus enables STA1 to determine the length/duration of the dataportion 1110 or the data portion 1110 and/or at least the portion of themidamble 1114. When the data portion 1110 is the last payload of the PHYdata unit 1100, the length and/or duration information in the VHT-SIGs(STA1) 1140 also indicates the end of the PHY data unit 100.

In one example, length and/or duration information includes anindication of the length of data and an indication of an MCS used totransmit the data, so that the duration can be determined using thelength of data and the indication of the MCS.

In some embodiments, the VHT-STF is omitted from the midambles 1112,1114. In some embodiments, the VHT-SIGs are omitted from the midambles1112, 1114 when all of the data portions (except the last one) have thesame length, which is indicated in the VHT-SIGs of the preamble 1104. Inone embodiment, VHT-TFs are omitted from the midambles 1112, 1114 whenthe VHT-TFs are included in the preamble 1104.

FIG. 31 is a diagram of another example single PHY data unit 1150 thatincludes data for STA1, according to an embodiment. The single PHY dataunit 1150 has a form a generally similar to the format of FIG. 30. TheL-SIG 122 field of the preamble 1104, however, indicates alength/duration of the first data portion 1106, as opposed to the entiredata unit 1150. Additionally, midambles 1154, 1158 have differentformats as compared to the midambles of FIG. 30. Midamble 1154 includesthe L-TFs 120, and an L-SIG 1162 that indicates a length/duration of thesecond data portion 1108. Similarly, midamble 1158 includes the L-TFs120, and an L-SIG 1166 that indicates a length/duration of the thirddata portion 1110.

FIG. 32 is a flow diagram of an example method 1200 for generating, andcontrolling the transmission of, an aggregated PHY data unit, accordingto an embodiment. The method 1200 is implemented by the PHY processingunit 20 (FIG. 1), in one embodiment. In other embodiments, the method1200 is implemented by another suitable apparatus, such as another PHYprocessing unit.

At block 1204, a plurality of individual PHY data units are generated.The individual PHY data units have independent data for a plurality ofrespective stations. The plurality of respective stations includes afirst station, a second station, and a third station.

At block 1208, an aggregated PHY data unit is generated, the aggregatedPHY data unit including the plurality of individual PHY data units ofblock 1204. The aggregated PHY data unit includes at least on midamble,and this midamble includes information that indicates a location of theindividual PHY data unit corresponding to the third station. In oneembodiment, the PHY data unit includes a preamble, and the preambleincludes information that indicates a location of the individual PHYdata unit corresponding to the second station. In one embodiment, themidamble is included in the individual PHY data unit corresponding tothe second station.

In one embodiment, the aggregated PHY data unit has a format such as inFIG. 9. In another embodiment, the aggregated PHY data unit has a formatsuch as in FIG. 12. In another embodiment, the aggregated PHY data unithas a format such as in FIG. 12. In another embodiment, the aggregatedPHY data unit has another suitable format.

At block 1212, while the information that indicates the location of theindividual PHY data unit corresponding to the third station istransmitted, the transmission is caused to be in an omnidirectionalmanner. For example, a beamforming unit is controlled to cause theomnidirectional transmission, in one embodiment.

At block 1216, while a payload of the individual PHY data unitcorresponding to the second station is being transmitted, beamforming tothe second station is performed.

In one embodiment, the blocks 1212 and 126 are omitted, and the method1200 is for generating an aggregated PHY data unit. In theseembodiments, the aggregated PHY data unit has a suitable format such asin FIG. 3-6, 9-13, etc.

FIG. 33 is a flow diagram of another example method 1240 for generating,and controlling the transmission of, an aggregated PHY data unit,according to another embodiment. The method 1240 is implemented by thePHY processing unit 20 (FIG. 1), in one embodiment. In otherembodiments, the method 1240 is implemented by another suitableapparatus, such as another PHY processing unit.

At block 1244, an aggregated PHY data unit is generated, the aggregatedPHY data unit including a plurality of individual PHY payloads. Theaggregated PHY data unit includes information that indicates locationsof at least some of the individual PHY payloads. In some embodiments,the aggregated PHY data unit includes a preamble. In some embodiments,the preamble includes information that indicates the locations of atleast some of the individual PHY payloads. In some embodiments, theaggregated PHY data unit includes at least one midamble. In someembodiments, one or more midambles include information that indicateslocations of at least some of the individual PHY payloads.

In one embodiment, the plurality of individual PHY payloads correspondsto a plurality of respective stations. In another embodiment, theplurality of individual PHY payloads corresponds to a single station.

In various embodiments, the aggregated PHY data unit has a suitableformat such as described above.

In some embodiments, each of at least one of the individual PHY payloadsis associated with a respective midamble of the aggregated PHY dataunit. In some embodiments, the aggregated PHY data unit does not includemidambles.

At block 1248, while information that indicates a location of anindividual PHY data unit is transmitted, the transmission is caused tobe in an omnidirectional manner. For example, a beamforming unit iscontrolled to cause the omnidirectional transmission, in one embodiment.

At block 1252, while a payload of the individual PHY data unitcorresponding to the second station is being transmitted, beamforming isperformed. For example, if the plurality of individual PHY payloadscorresponds to a plurality of respective stations, beamforming is to therespective station.

In one embodiment, the blocks 1248 and 1252 are omitted, and the method1240 is for generating an aggregated PHY data unit. In theseembodiments, the aggregated PHY data unit has a suitable format such asin FIG. 3-6, 8-13, 15B, 30, etc.

FIG. 34 is a flow diagram of another example method 1270 for generating,and controlling the transmission of, an aggregated PHY data unit,according to another embodiment. The method 1270 is implemented by thePHY processing unit 20 (FIG. 1), in one embodiment. In otherembodiments, the method 1270 is implemented by another suitableapparatus, such as another PHY processing unit.

At block 1274, a PHY data unit including a payload for a first stationis generated. At block 1278, beamforming to the first station isperformed while the PHY data unit generated at block 1274 istransmitted.

At block 1282, an aggregated PHY data unit is generated. The aggregatedPHY data unit includes a plurality of individual PHY data unitsincluding first and second PHY data units corresponding to the firststation and a second station. In some embodiments, the aggregated PHYdata unit has a format such as in FIG. 10 or FIG. 11, or anothersuitable format.

At block 1286, transmission in an omnidirectional manner is caused whilethe entire aggregated PHY data unit is transmitted.

FIG. 35 is a block diagram of an example PHY processing unit 1300 thatis utilized in some embodiments. In PHY processing unit 1300 includes abeamforming unit 1304.

In some embodiments, the PHY processing unit 1300 is configured toimplement one or more of the methods 1200 (FIG. 32), 1240 (FIG. 33),and/or 1270 (FIG. 34).

FIG. 36 is a flow diagram of an example method 1330 for processing areceived aggregated PHY data unit, according to one embodiment. Themethod 1330 is implemented by the PHY processing unit 29 (FIG. 1), inone embodiment. In other embodiments, the method 1330 is implemented byanother suitable apparatus, such as the PHY processing unit 1300 of FIG.35 or another suitable PHY processing unit.

At block 1334, a duration of the aggregated PHY data unit is determined.In one embodiment, the duration is determined based on information in apreamble of the aggregated PHY data unit.

At block 1338, an expected location of a first midamble of theaggregated PHY data unit is determined. In one embodiment, the expectedlocation of the first midamble is determined based on information in thepreamble of the aggregated PHY data unit. In another embodiment, theexpected location of the first midamble is determined based oninformation in another midamble of the aggregated PHY data unit.

At block 1342, when the first midamble is not detected at the expectedlocation, the communication channel is scanned for a second midamble ofthe aggregated PHY data unit during the duration of the PHY data unit.In some embodiments, scanning is ended prior to the end of the durationof the aggregated PHY data unit. In other embodiments, scanning is endedafter the end of the duration of the aggregated PHY data unit.

FIG. 37 is a flow diagram of another example method 1370 for processinga received aggregated PHY data unit, according to another embodiment.The method 1370 is implemented by the PHY processing unit 29 (FIG. 1),in one embodiment. In other embodiments, the method 1370 is implementedby another suitable apparatus, such as the PHY processing unit 1300 ofFIG. 35 or another suitable PHY processing unit.

In one embodiment, the aggregated PHY data unit includes a preamble, atleast first, second, and third PHY data units, and the second PHY dataunit has associated therewith a midamble of the aggregated data unit.

At block 1374, an expected location of the second individual PHY dataunit of the aggregated PHY data unit is determined based on informationin the preamble.

At block 1378, an expected location of the third individual PHY dataunit of the aggregated PHY data unit is determined based on informationin the midamble.

The IEEE 802.11n Standard defines various parameters related to the MAClayer. For example, the maximum size of a MAC service data unit (MSDU)is 2,304 bytes (B). As another example, the maximum size of an MSDU(A-MSDU) is either 3,839 B or 7,935 B. The maximum A-MSDU size isspecified with a one-bit subfield in a high-throughput (HT) capabilitiesinformation element (IE).

As another example, the maximum size of a MAC protocol data unit (MPDU)in an aggregated MPDU (A-MPDU) is 4,095 B. The maximum size of an A-MPDUin an IEEE 802.11n PHY protocol data unit (PPDU) is 8,191 B to 65,535 B,and can be specified with an A-MPDU capabilities field in the HTcapabilities IE.

In some embodiments, it is beneficial to use larger A-MPDU's as comparedto the maximum A-MPDU size of IEEE 802.11n. For example, withcommunication systems having larger bandwidth than that of IEEE 802.11n,a given length PHY payload will have shorter duration, but may have thesame preamble duration. Thus, there will be more preamble overhead.

In one embodiment, the maximum PPDU duration is limited by an L-SIGfield in a preamble of the PPDU that indicates the number of symbols.For example, if the maximum value of this L-SIG field is 1365, and ifeach symbol duration is 4 microseconds (μs), the maximum PPDU durationis 5.46 milliseconds (ms). This corresponds to about 666 kilobytes (KB)for transmission at 1 Gbps, and 1.3 megabytes (MB) at 2 Gbps. If amaximum BA window is kept unchanged at 64, in order to have an A-MPDU ofup to 1 MB, the maximum MPDU size should be increased to 1 MB/64=16 KB,in one embodiment. The maximum A-MSDU size should also be increased to16 KB, in one embodiment. In one embodiment, the increased maximum MPDUsize and the increased maximum A-MSDU size supports a jumbo Ethernetframe of 9000 B.

FIG. 38 is a block diagram of an example A-MPDU frame format, accordingto an embodiment. An MPDU length field has a length of 14 bits to permita maximum MPDU length of 16 KB. An end-of-file (EOF) is either B0 or B1,in an embodiment. In one embodiment, the CRC field is reduced to 4 bitsas compared to IEEE 802.11n.

A 32-bit CRC is not effective for MPDUs longer than 12,000 B, in someembodiments and/or implementations. For example, the probability ofundetected errors remains constant for frame sizes between 3007 bits and91,639 bits (approximated 376 to 11,455 B). In one embodiment, themaximum MPDU is limited to 12 KB (or 11,455 B). In another embodiment,the maximum MPDU is limited to 8 KB, with a one bit MPDU lengthextension as compared to IEEE 802.11n. In one embodiment, the maximumA-MPDU size is 64*12 KB=768 KB.

In some embodiments, stations negotiate frame sizes. In one embodiment,a maximum A-MSDU length subfield is used to specify a desired lengthfrom a plurality of possible lengths. In one embodiment, the maximumA-MSDU length subfield is 2-bits (e.g., (e.g., 0: 3,839 B; 1: 7,935 B;2: ˜12 KB; or 0: 3,839 B; 1: 7,935 B; 2: ˜12 KB; 3: ˜16 KB). In oneembodiment, a maximum A-MPDU exponent subfield is used to specify adesired length from a plurality of possible lengths. In one embodiment,the maximum A-MPDU exponent subfield is 3-bits (e.g., (2¹³−1)B˜(2¹³⁺⁶−1) B, or (2¹³−1) B˜(2¹³⁺⁷−1) B). In one embodiment, a maximumMSDU length subfield is used to specify a desired length from aplurality of possible lengths. In one embodiment, the maximum A-MSDUlength subfield is 1-bit (e.g., 0: 2304 B; 1: ˜4350 B, or 0: 2304 B; 1:˜9000 B, or 0: 2304 B; 1: suitable value above 9000 B).

In some embodiments, it is beneficial to support larger MSDUs ascompared to IEEE 802.11n, for more efficient A-MSDUs and larger A-MPDUswithout A-MSDU support, for example. In IEEE 802.11n, the maximum MSDUsize is limited by the lowest modulation coding scheme (MCS), i.e., MCSO(6.5 Mbps). For example, the maximum length specified by L-SIG is 5.46ms, and the preamble overhead is 5/6 symbols. The data field of a PPDUcan be a maximum of 5.44 ms. With MCSO, the maximum data field can beapproximately 4420 B. Thus, the maximum MSDU (excluding a service field,a delimiter, a MAC header, a frame check sequence (FCS), PHY padding,and tail bits) is approximately 4350 B.

For jumbo Ethernet frames (9000 B), if the maximum MSDU size isincreased to 9000 B, with a maximum data field of 5.44 ms, the minimumMCS that can be used is 13.5 Mbps (i.e., an MCS lower than 13.5 Mbps isnot allowed to transmit a 9000 B MSDU).

In one embodiment, a transmitter determines a minimum allowed MCS basedon one or more of a PPDU size, an MPDU size, or a MSDU size, andtransmits the PPDU/MPDU/MSDU using an MCS that meets or exceeds thedetermined minimum allowed MCS. In another embodiment, a MAC processingunit is configured to fragment a long MSDU and transmit the fragmentedMSDUs using a MCS lower than the determined minimum allowed MCS for thelong MSDU. In another embodiment, a MAC processing unit causes a networkmaximum transmission unit (MTU) to be reduced (e.g., to 1500 B) in orderso that a lower MCS can be utilized, e.g., when channel conditions donot support the determined minimum allowed MCS.

FIG. 39 is a flow diagram of an example method 1400 for controllingtransmission in a wireless network, according to an embodiment. Themethod 1400 is implemented by a suitable PHY processing unit such as thePHY processing unit 20 (FIG. 1), the PHY processing unit 29 (FIG. 1),the PHY processing unit 1300 (FIG. 35), etc.

At block 1404, a minimum MCS is determined based on a PHY data unit sizeor a MAC data unit size. In one embodiment, the minimum MCS isdetermined based on a PPDU size. In another embodiment, the minimum MCSis determined based on a MPDU size. In another embodiment, the minimumMCS is determined based on a MSDU size.

At block 1408, data units are caused to be transmitted according to anMCS that is equal to or exceeds the minimum MCS determined at block1404. In one embodiment, an MCS that is equal to or exceeds the minimumMCS is an MCS that provides a throughput equal to or greater than athroughput provided by the minimum MCS. In another embodiment, an MCSthat is equal to or exceeds the minimum MCS is an MCS that provides aneffective data rate equal to or greater than an effective data rateprovided by the minimum MCS.

FIG. 40 is a flow diagram of another example method 1440 for controllingtransmission in a wireless network, according to another embodiment. Themethod 1440 is implemented by a suitable MAC processing unit such as theMAC processing unit 18 (FIG. 1), the MAC processing unit 28 (FIG. 1),etc.

At block 1444, a minimum MCS is determined based on a PHY data unit sizeor a MAC data unit size. In one embodiment, the minimum MCS isdetermined based on a PPDU size. In another embodiment, the minimum MCSis determined based on a MPDU size. In another embodiment, the minimumMCS is determined based on a MSDU size.

At block 1448, it is determined whether the minimum MCS determined atblock 1444 is supported by the communication channel. In one embodiment,a PHY processing unit determines a maximum MCS supported by the channeland informs the MAC processing unit, and the MAC processing unitdetermines whether the minimum MCS determined at block 1444 is supportedby the communication channel based on the maximum MCS supported by thechannel as determined by the PHY processing unit.

At block 1452, if it is determined that the minimum MCS determined atblock 1444 is not supported by the channel, a MAC data unit isfragmented into smaller fragments so that transmission of the fragmentsare supported by the channel. For example, in one embodiment, a longMSDU is fragmented into smaller MSDUs.

FIG. 41 is a flow diagram of another example method 1480 for controllingtransmission in a wireless network, according to another embodiment. Themethod 1480 is implemented by a suitable MAC processing unit such as theMAC processing unit 18 (FIG. 1), the MAC processing unit 28 (FIG. 1),etc.

At block 1484, a minimum MCS is determined based on a PHY data unit sizeor a MAC data unit size. In one embodiment, the minimum MCS isdetermined based on a PPDU size. In another embodiment, the minimum MCSis determined based on a MPDU size. In another embodiment, the minimumMCS is determined based on a MSDU size.

At block 1488, it is determined whether the minimum MCS determined atblock 1444 is supported by the communication channel. In one embodiment,a PHY processing unit determines a maximum MCS supported by the channeland informs the MAC processing unit, and the MAC processing unitdetermines whether the minimum MCS determined at block 1444 is supportedby the communication channel based on the maximum MCS supported by thechannel as determined by the PHY processing unit.

At block 1492, if it is determined that the minimum MCS determined atblock 1444 is not supported by the channel, a network MTU size isreduced so that resulting MAC data units are supported by the channel.For example, in one embodiment, a MTU size greater than 1500 B (e.g.,9000 B) is reduced to 1500 B or less. In one embodiment, the MACprocessing unit sends a signal to a processor that implements a protocollevel higher than MAC to reduce the MTU, e.g., an Ethernet MTU.

In some embodiments, the method 1400 (FIG. 39) is combined with themethod 1440 (FIG. 40) or the method 1480 (FIG. 41). For example, if itis determined that the minimum MCS is supported by the communicationchannel, block 1408 is implemented. On the other hand, if it isdetermined that the minimum MCS is not supported by the communicationchannel, block 1452 or block 1492 is implemented.

In IEEE 802.11n, stations can negotiate buffer size (i.e., number ofbuffers) when setting a BA agreement per traffic identifier (TID). Astation capable of supporting a maximum MSDU/A-MSDU, but with limitedbuffer space must request a small buffer size (i.e., much less than 64)for each BA/TID session. A small buffer size leads to a small BA window,which reduces MAC efficiency for an A-MPDU with small size MPDUs. It isbeneficial, in some embodiments and/or scenarios, to negotiate both abuffer size (i.e., a number of buffers) and a maximum MPDU size perBA/TID.

FIG. 42 is a flow diagram of an example method 1500 for controllingtransmission in a wireless network, according to an embodiment. Themethod 1500 is implemented by a suitable MAC processing unit such as theMAC processing unit 18 (FIG. 1), the MAC processing unit 28 (FIG. 1),etc.

At block 1504, a desired buffer size (i.e., a number of buffers) for aparticular BA session and/or a particular TID is determined. At block1508, a desired maximum MAC data unit size (e.g., a maximum MPDU size)for the particular BA session and/or the particular TID is determined.At block 1512, indications of the desired buffer size and the desiredmaximum MAC data unit size are caused to be transmitted to anotherstation with which the BA/TID session is to be performed. In oneembodiment, block 1512 comprises including the indications in a singleMAC IE. In another embodiment, each indication is included in a separateMAC IE. In one embodiment, an indication of the maximum MAC data unitsize is included in an add BA parameter set field of an extended add BArequest frame. In one embodiment, the indication of the maximum MAC dataunit size is a 2-bit field (e.g., 0: 2 KB; 1: 4 KB; 2: 8 KB; 3: 12 KB,or 0: 2 KB; 1: 4 KB; 2: 8 KB; 3: 16 KB).

At least some of the various blocks, operations, and techniquesdescribed above may be implemented in hardware, a processor executingfirmware and/or software instructions, or any combination thereof. Whenimplemented utilizing a processor executing software or firmwareinstructions, the software or firmware instructions may be stored in anycomputer readable memory such as on a magnetic disk, an optical disk, orother tangible storage medium, in a RAM or ROM or flash memory,processor, hard disk drive, optical disk drive, tape drive, etc.Likewise, the software or firmware instructions may be delivered to auser or a system via any known or desired delivery method including, forexample, on a computer readable disk or other transportable, tangiblecomputer storage mechanism or via communication media. Communicationmedia typically embodies computer readable instructions, datastructures, program modules or other data in a modulated data signalsuch as a carrier wave or other transport mechanism. The term “modulateddata signal” means a signal that has one or more of its characteristicsset or changed in such a manner as to encode information in the signal.By way of example, and not limitation, communication media includeswired media such as a wired network or direct-wired connection, andwireless media such as acoustic, radio frequency, infrared and otherwireless media. Thus, the software or firmware instructions may bedelivered to a user or a system via a communication channel such as atelephone line, a DSL line, a cable television line, a fiber opticsline, a wireless communication channel, the Internet, etc. (which areviewed as being the same as or interchangeable with providing suchsoftware via a transportable storage medium). The software or firmwareinstructions may include machine readable instructions stored on amemory of other computer-readable storage medium that, when executed bythe processor, cause the processor to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method, comprising: generating an aggregatedphysical layer (PHY) data unit for transmission of independent data fora plurality of stations via a communication channel, wherein theaggregated PHY data unit includes i) a plurality of individual PHY dataunits corresponding to the plurality of stations, ii) a midambleincluded in one of the plurality of individual PHY data units, and iii)information that indicates locations of at least some of the pluralityof individual PHY data units within the aggregated PHY data unit, andwherein at least some of the information that indicates locations of atleast some of the plurality of individual PHY data units is included inthe midamble; controlling beamforming while the aggregated PHY data unitis being transmitted, including: i) causing transmission in anomnidirectional or quasi-omnidirectional manner while the informationthat indicates locations of at least some of the plurality of individualPHY data units is transmitting, and ii) for each of the individual PHYdata units, beamforming to the corresponding station while at least someof the corresponding individual PHY data unit is being transmitted. 2.The method according to claim 1, wherein generating the aggregated PHYdata unit comprises generating a preamble of the aggregated PHY dataunit that includes some of the information that indicates locations ofat least some of the plurality of individual PHY data units.
 3. Themethod according to claim 2, wherein controlling beamforming while theaggregated PHY data unit is being transmitted comprises: causingtransmission in an omnidirectional or quasi-omnidirectional manner whilea first portion of the preamble is transmitting; and beamforming to oneof the stations in the plurality of stations while a second portion ofthe preamble is transmitting.
 4. The method according to claim 3,wherein the second portion of the preamble includes training fieldsassociated with the one station.
 5. The method according to claim 1,wherein controlling beamforming while the aggregated PHY data unit isbeing transmitted comprises: causing transmission in an omnidirectionalor quasi-omnidirectional manner while a first portion of the midamble istransmitting; and beamforming to one of the stations in the plurality ofstations while a second portion of the midamble is transmitting.
 6. Themethod according to claim 5, wherein the second portion of the midambleincludes training fields associated with the one station.
 7. The methodaccording to claim 1, wherein controlling beamforming while theaggregated PHY data unit is being transmitted comprises: causingtransmission in an omnidirectional or quasi-omnidirectional manner whilethe midamble is transmitting; and beamforming to one of the stations inthe plurality of stations while a payload of the one individual PHY dataunit is transmitting.
 8. An apparatus, comprising: a physical layer(PHY) processing unit to generate a PHY data unit for transmission ofindependent data for a plurality of stations via a communicationchannel, wherein the aggregated PHY data unit includes i) a plurality ofindividual PHY data units corresponding to the plurality of stations,ii) a midamble located in one of the plurality of individual PHY dataunits, and iii) information that indicates locations of at least some ofthe plurality of individual PHY data units within the aggregated PHYdata unit, and wherein at least some of the information that indicateslocations of at least some of the plurality of individual PHY data unitsis included in the midamble; wherein the PHY processing unit includes abeamforming unit to: i) cause transmission in an omnidirectional orquasi-omnidirectional manner while the information that indicateslocations of at least some of the plurality of individual PHY data unitsis transmitting, and ii) for each of the individual PHY data units,beamform to the corresponding station while at least some of thecorresponding individual PHY data unit is being transmitted.
 9. Theapparatus according to claim 8, wherein the PHY processing unit isconfigured to generate a preamble of the aggregated PHY data unit thatincludes some of the information that indicates locations of at leastsome of the plurality of individual PHY data units.
 10. The apparatusaccording to claim 9, wherein the beamforming unit is configured to:cause transmission in an omnidirectional or quasi-omnidirectional mannerwhile a first portion of the preamble is transmitting; and beamform toone of the stations in the plurality of stations while a second portionof the preamble is transmitting.
 11. The apparatus according to claim10, wherein the second portion of the preamble includes training fieldsassociated with the one station.
 12. The apparatus according to claim 8,wherein the beamforming unit is configured to: cause transmission in anomnidirectional or quasi-omnidirectional manner while a first portion ofthe midamble is transmitting; and beamforming to one of the stations inthe plurality of stations while a second portion of the midamble istransmitting.
 13. The apparatus according to claim 12, wherein thesecond portion of the midamble includes training fields associated withthe one station.
 14. The apparatus according to claim 8, wherein thebeamforming unit is configured to: cause transmission in anomnidirectional or quasi-omnidirectional manner while the midamble istransmitting; and beamform to one of the stations in the plurality ofstations while a payload of the one individual PHY data unit istransmitting.